I am learning rust now, but D seems quite promising.
Rust guides you more toward certain approaches. That makes rust easier to learn, but it makes it harder to integrate with existing projects. On paper, rust could work great in a lot of environments, but I'm finding that it takes a bit more work to integrate with a real codebase. It can be done, and I feel like that's well supported, but it takes some real work to port the concepts of a C API into a good and safe rust API.
D might make that easier because it's an "everything" language, so there is likely a corresponding D equivalent of almost any existing API. Of course, you won't get the same level of safety or other benefits, but it could be a smoother path.
Rust guides you more toward certain approaches. That makes rust easier to learn, but it makes it harder to integrate with existing projects. On paper, rust could work great in a lot of environments, but I'm finding that it takes a bit more work to integrate with a real codebase. It can be done, and I feel like that's well supported, but it takes some real work to port the concepts of a C API into a good and safe rust API.
D might make that easier because it's an "everything" language, so there is likely a corresponding D equivalent of almost any existing API. Of course, you won't get the same level of safety or other benefits, but it could be a smoother path.